Abstract: Method and apparatus for producing high grade phosphate rock from low grades, slime or tailings by subjecting the low grade rock, slime or tailings to a calcination treatment at a temperature within the range from 1000.degree. F. to 1600.degree. F., and preferably from 1400.degree. F. to 1600.degree. F., until a fraction of said rock, slime or tailings becomes magnetically attractable, and subjecting the treated material to a high strength magnetic field to separate the same magnetically into at least two fractions, one of increased BPL and one of decreased BPL.